The present invention relates to an automatic glue spraying machine for screws, in which a rotary disk of the conveying device is formed with peripheral notches serving to space the screws from each other at equal intervals and stably convey the screws without jamming or swinging thereof. A telescopic tube body supporting the glue sprayers is vertically adjustable according to the length of position of the screws and the rotary disk of the conveying device is replaceable with another rotary disk with peripheral notches suitable for the diameter of the screws so that the glue spraying machine is applicable to various diameters and lengths of screws. During glue spraying operation, a store is created in the air chamber of the main body of the sprayer to previously evenly stir the glue powder and then evenly spray out the glue powder to the desired section of the screw. Therefore, a better glue spraying operation is achieved.
FIGS. 1 and 2 show a conventional glue spraying machine for screws and the glue spraying operation thereof. The conveying device 10 of the conventional glue spraying machine is composed of two rollers 11 and two parallel conveying belts 12 drivingly wound on the rollers 11. A high frequency heater 28 is disposed between the rollers 11 and two glue nozzles 30 are disposed at a rear section of the conveying device 10. A glue recovering sucker 31 is disposed opposite to the glue sprayers 30. In use, a vibrator vibrates to upward move the screws along a spiral slope face thereof into the space between the parallel conveying belts 12 with the head of the screw hung on the upper sides of the conveying belts 12, while the stem of the screw suspended therefrom. When the screws are heated through the high frequency heater 20, the screws are heated thereby to a desired high temperature. Thereafter, the screws are further conveyed forward through the glue nozzles 30. At this time, the glue powder is sprayed out from the glue nozzles 30 toward the predetermined position of the screw. The high temperature of the screw itself then instantaneously melts the glue powder to adhere to the screw. After the glue spraying operation is completed, the excessive glue powder is recovered by the recovering sucker 31. The glued screws are further conveyed by the parallel conveying belts 12 to fall onto a large conveying belt to be conveyed and cooled.
Several shortcomings exist in the above arrangements as follows:
1. The parallel conveying belts 12 fail to space the screws from each other at equal intervals. Moreover, when revolving, the conveying belts 12 tend to shock. Therefore, when conveyed, the screws are apt to jam together and swing. This greatly affects the quality and effect of the glue spraying operation. PA1 2. The pitch between the two conveying belts 12 is fixed and the positions of the two glue nozzles 30 are also fixed so that the glue spraying machine is only applicable to screws with a specific range of diameter and length. PA1 3. The glue nozzles 30 directly spray the glue powder to the screws without previous stirring so that the glue powder can be hardly evenly sprayed onto the screws.